Our Nearest Star Has a Planet, and These Are the Ways It Could Be Habitable

A couple years ago, I was part of the team that discovered the first Earth-sized planet, Kepler-186f, rotating comfortably in its star’s “habitable zone,” where water can be liquid. Its sun, Kepler 186, is faint and far away from us—and a little colder than we’d like if we were to settle there—but it does have the potential for life. Nevertheless, Kepler 186f, please see yourself off the “best candidate habitable worlds” shelf.

And the same goes for you, Kepler-62f, Gliese 667Cc, and Kepler-452b. Sure, you are all fascinating planets, but there’s something not quite ideal about each of you: Either your host star is so faint that we won’t be able to learn more about you for decades, or you’re quite a bit larger than Earth, and we’re not sure you are a true rocky planet—for all we know, you could be a masquerading “.” So move aside! There’s a new standard in town, and its name is Proxima b. This planet has